Process for purifying citrus oils



States Patent Office Patented Dec. 9, 1958' PROCESS FOR PURIFYING CITRUS OILS William C. Platt, Glendora, Califi, assignor to Ventura Processors, Ventura, Califi, a corporation of California No Drawing. Application June 25, 1956 Serial No. 593,361

6 Claims. (Cl. 260236.6)

process for purifying citrus removal of waxy substances This invention relates to a oils and in particular to the from lemon oil.

One object of the invention is to provide a process for treating citrus oils which removes the impurities that cause cloudiness in the oils upon chilling or standing. Another object is to provide a pre-treating process for citrus oils which facilitates the subsequent removal of waxy substances by chilling.

These and other objects are attained by my invention which will now be described in detail.

Citrus oils, and particularly lemon oil, cannot be satisfactorily dewaxed by cooling and separating out the wax crystals, because much of the wax does not crystallize or separate by a simple chilling procedure. This is believed to be caused by the presence of minute amounts of some impurities other than wax or pectins, which act as protective agents to prevent the wax from crystallizing on cooling.

I have discovered that a pre-washing of the impure citrus oil with an aqueous buffered liquid containing active esterase enzymes causes destruction or inactivation of the protective materials which inhibit wax separation, and permits substantially complete wax removal by a subsequent chilling processing of the pre-treated citrus oil.

As an example illustrating my invention, 100 gallons of lemon oil was treated with 38 gallons of aqueous buffer solution of pH 4.0 to 4.5, and 0.35 pounds of Pectinol (Rohm and Haas, esterase enzyme preparation, 10-M. Factor 3.87). The buffer solution of pH 4.0 to 4.5 was made by dissolving 8.31 pounds of sodium citrate and 4.58 pounds of citric acid in water to make 100 gallons. The mixture was heated to 130 F. and agitated for four hours, and then allowed to cool and stand without agitation for at least twelve hours, after which the mixture was passed through a centrifuge and a clear oil product recovered. This pre-treated oil was then cooled to 45 F. in a refrigerated tank, with slow agitation, for about seventy-two hours, following which the agitation was discontinued and the batch allowed to settle for twenty-four hours. The mixture of oil and wax crystals was then centrifuged, and a substantially wax free lemon oil recovered. The final product does not shown any cloud when tested by a standard testing procedure which consists of adding 3 parts by volume of 95% alcohol to 1 part by volume of the oil at 77 F., and after shaking, visually observing the clarity.

Other specific esterase enzyme preparations of the hydrolase type which under buffered conditions Within the range of pH 4 to 7 convert pectin compounds to pectic or related acids and alcohol, may be employed in my process. The standardized product specified in the above example is preferred, although other standardized grades of Pectinol from the same source or for another example Pektizyme brand of pectinase enzymes from Takamine Laboratory, Inc. may be employed. The use of these enzymes in a buffering solution in the range of pH 4.0 to 4.5 appears to most effectively overcome the wax inhibiting effect, and control within this pH range is a preferred condition.

While I prefer to use the process as described above, I may shorten the process by omitting the centrifuging step to separate the buffer solution from the pre-treated oil, and may chill the entire mixture, or the decanted oil fraction, after the enzymes have been allowed to act, and separate the purified oil from the water, wax, and other impurities, after chilling and settling, in a single centrifuging operation.

The optimum proportions of the buffer solution containing the enzyme preparation must be selected in accordance with the quality and kind of citrus oil being treated. The above proportions were found to be effective for a crude lemon oil containing about two percent wax. The same conditions have been found to be effective on orange oil. Citrus oils which hove been dewaxed by the usual simple chilling procedure, and which fail to pass the clarity test visually, or by the alcohol solution test, described previously, may be retreated by the enzyme washing operation and then chilled to produce high quality wax free oil.

My process is equally applicable to other citrus oils such as orange oil, grapefruit oil, tangerine oil and the like, with suitable variations in the proportions to effect the complete removal of the wax content, following the procedures given asapplied specifically to lemon oil.

I claim:

1. The process for destroying wax crystallization inhibitors in impure citrus oils which comprises the steps of subjecting said impure citrus oils to a washing treat ment with a buffered aqueous dispersion of pH range from 4.0 to 4.5 of a pectase enzyme capable of enzymatic destruction of the contained inhibitor in said citrus oil While maintaining a temperature within a range substantially above the freezing point of the aqueous dispersion but below the inactivating temperature of the said enzyme, for a period of time sufiicient to allow enzymic action by said enzyme upon said inhibitor; and then separating the aqueous portion from the oily portion of the mixture of said enzyme aqueous dispersion and citrus oil.

2. The process of removing dissolved waxy substances from a clear citrus oil comprising the steps of agitating the oil with a buffered aqueous liquid having a pH range of about 4.0 to 7.0 containing esterase enzymes capable of destroying wax-crystallization-inhibiting compounds while maintaining a temperature within a range substantially above the freezing point of the aqueous liquid but below the inactivating temperature of said enzyme, for a period of time sufficient to allow enzymic action by said enzyme upon said inhibitor; separating the treated oil from the aqueous solution; chilling the oil to crystallize the contained wax; and separating the cold oil from the wax.

3. The process of removing dissolved waxy substances from a clear citrus oil comprising the steps of agitating the oil with a buffered aqueous liquid having a pH range of about 4.0 to 7.0 and containing active pectase enzymes; while maintaining a temperature within a range substantially above the freezing point of the aqueous liquid but below the inactivating temperature of said enzyme, for a period of time sulficient to allow enzymic action by said enzyme upon said inhibitor; separating the treated oil from the aqueous solution; chilling the oil to crystallize the contained wax; and separating the cold oil from the wax.

4. The process of removing dissolving waxy substances from a clear citrus oil comprising the steps of agitating the oil with a buffered aqueous liquid having a pH in the range of 4.0 to 4.5 and containing active pectase enzymes while maintaining a temperature within a range substantially above the freezing point of the aqueous liquid but below the inactivating temperature of said enzyme, for a period of time sufficient to allow enzyrnic action by said enzyme upon said inhibitor; separating the treated oil from the aqueous solution; chilling the oil to crystallize the contained wax; and centrifuging the chilled oil to separate out the wax.

5. The process of removing dissolved waxy substances from a clear citrus oil comprising the steps of agitating the oil with a buffered aqueous liquid having a pH in the range of 4.0 to 4.5 and containing active pcctase enzyme while maintaining a temperature within a range substantially above the freezing point of the aqueous liquid but below the inactivating temperature of said enzyme, for a period of time sutficient to allow enzymic action by said enzyme upon said inhibitor; chilling the mixture of aqueous solution and oil to crystallize the contained was; and separating the cold oil from the wax and aqueous solution.

i the inactivating temperature of said enzyme, for a period of time suliicient to allow enzymic action by said cnzymc upon said inhibitor.

References Cited in the tile of this patent UNITED STATES PATENTS Barnes et al May 16, 1939 Beckrnan Nov. 1, 1949 

1. THE PROCESS FOR DESTROYING WAX CRYSTALLIZATION INHIBITORS IN IMPURE CITRUS OILS WHICH COMPRISES THE STEPS OF SUBJECTING SAID IMPURE CITRUS OILS TO A WASHING TREATMENT WITH A BUFFERED AQUEOUS DISPERSION OF PH RANGE FROM 4.0 TO 4.5 OF A PECTASE ENZYME CAPABLE OF ENZYMATIC DESTRUCTION OF THE CONTAINED INHIBITOR IN SAID CITRUS OIL WHILE MAINTAINING A TEMPERATURE WITHIN A RANGE SUBSTANTIALLY ABOVE THE FREEZING POINT OF THE AQUEOUS DISPERSION BUT BELOW THE INACTIVATING TEMPERATURE OF THE SAID ENZYME, FOR A PERIOD OF TIME SUFFICIENT TO ALLOW ENZYMIC ACTION BY SAID ENZYME UPON SAID INHIBITOR; AND THEN SEPARATING THE AQUEOUS PORTION FROM THE OILY PORTION OF THE MIXTURE OF SAID ENZYME AQUEOUS DISPERSION AND CITRUS OIL. 